The Kempston Interface, produced by Kempston Micro Electronics

Kempston Micro Electronics

Kempston Micro Electronics was an electronics company specialising in computer joysticks and related home computer peripherals during the 1980s. Kempston was based in Kempston, Bedfordshire, England.- Interfaces :...

, was the generic name for any interface on Sinclair

Sinclair Research Ltd

Sinclair Research Ltd is a British consumer electronics company founded by Sir Clive Sinclair in Cambridge. Originally incorporated in 1973 as Ablesdeal Ltd., it remained dormant until 1976, and did not adopt the name Sinclair Research until 1981....

's ZX Spectrum

ZX Spectrum

The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...

 series of computers that allowed joystick

Joystick

A joystick is an input device consisting of a stick that pivots on a base and reports its angle or direction to the device it is controlling. Joysticks, also known as 'control columns', are the principal control in the cockpit of many civilian and military aircraft, either as a center stick or...

s complying with the de facto Atari 2600

Atari 2600

The Atari 2600 is a video game console released in October 1977 by Atari, Inc. It is credited with popularizing the use of microprocessor-based hardware and cartridges containing game code, instead of having non-microprocessor dedicated hardware with all games built in...

 standard to be used with the machine. It was one of the most widely supported standards on the machine. The interface itself would be attached to the computer's rear expansion port with a single joystick port on the front or top of the system.

It came out as the clear winner against other standards such as Protek's cursor-based solution and the Fuller standard during the days of the 48K Spectrum. However, when Amstrad

Amstrad

Amstrad is a British electronics company, now wholly owned by BSkyB. As of 2006, Amstrad's main business is manufacturing Sky Digital interactive boxes....

 released the ZX Spectrum +2, the computer featured a built-in joystick interface that was software-compatible with Sinclair's ZX Interface 2

ZX Interface 2

The ZX Interface 2 was a peripheral from Sinclair Research for its ZX Spectrum home computer released in September 1983. It had two joystick ports and a ROM cartridge slot, which offered instant loading times. The joystick ports were not compatible with the popular Kempston interface, and thus...

standard. Unfortunately, the bundled SJS-1 joystick was electrically incompatible with the Atari standard. The Interface 2 standard simulated keypresses on the numerical keys (1->5 and 6->0 being left, right, down, up, fire for the 'left' and 'right' joysticks respectively) and hence were ideal for games with no official joystick support but in which the keys could be redefined.

Problems had also been reported with the Kempston Interface breaking down on the newer models and it faded slowly into obscurity, although the option to use Kempston joysticks remained in games until the end of the computer's shelf life.